Smart cards could get smarter and fitness bands more fit with a new chip from Freescale Semiconductor that's as thin as a blade of grass.

The company's latest sliver of silicon for low-powered devices like payment cards, wearables and medical sensors is just 0.34mm thick. It's the kind of chip that's needed for the Internet of Things, where a little bit of processing goes a long way but there's not much space or power to do the work.

The Kinetis K22 is an MCU (microcontroller unit), a low-power embedded chip with built-in memory that can be programmed to carry out specific tasks. An MCU isn't as powerful as the microprocessors in devices like PCs and phones, with full OSes and displays, but it can power smaller, dedicated devices that don't have to be charged every night. Some MCUs also include radios for systems like Bluetooth Low Energy, said Steven Tateosian, manager of microcontroller systems at Freescale.

The new chip is about half as thick as the current generation of MCUs and is 4.1mm by 3.6mm in size. Its thin profile lets the K22 fit into ordinary payment and access cards, which are about three-quarters of a millimeter thick. That gives manufacturers a way to add more features without stepping up to a thicker design, which in the case of payment cards is not even an option, Tateosian said.

The intelligence and memory in an MCU could beef up security features in standard cards. For example, a key card in an office could include encrypted information about the person holding it and their access privileges. That could lead to policy-based access controls that are more sophisticated than current magnetic or RFID cards programmed by an administrator, Tateosian said.

In payment cards, the chip could allow cards with E Ink-type displays to show more information, including messages sent from the card issuer. Eventually, cardholders might be able to enter a PIN or draw a shape on a capacitive touch surface on a card while they're in line at the store, Tateosian said. The computing power of a thin MCU could help make that possible.

In other types of devices, the thinner chip gives designers more flexibility -- even literally. It bends more easily than thicker MCUs and is small enough to fit into products that bend and stretch. One potential use is in a glucose monitor in a stretchable electronic patch that adheres to skin. That monitor might even take the form of an implant that goes under the patient's skin, Tateosian said. And in the case of a wearable like a smartwatch, any component that's thinner can make the final product smaller.

Device makers can get the K22 in large enough quantities to mass-produce products now, and it costs roughly the same as comparable chips that aren't as thin, Tateosian said. Freescale plans to make the rest of its Kinetis line of MCUs thinner, too.